Presentation at ISAE 2019 - Bergen, Norway

Summary

The FreeBirds project aims to generate more insight into the relationship between organic chickens’ free-range use and bird health, welfare and performance, as well as soil nutrient load. One completed study of the project compared the range use, welfare and performance of Dekalb White (DW) and Bovans’ Brown (BB) laying hens on an experimental setting simulating organic on-farm conditions. Six hundred non-beak-trimmed hens of each hybrid (N = 1200) were housed in groups of 100, from 17 to 38 weeks of age, in 12 pens according to EU requirements for organic egg production. Indoor pens measured 4.5 × 4.5 m. Each pen provided 12 nest boxes and 18 cm/hen of elevated perch length. Wood shavings was provided as litter and the indoor net stocking density was 5.1 hens/m2. The outdoor range for each pen measured 4.5 × 90 m, providing an outdoor density of 4 m2/hen. The ground on the outdoor range had grass covering but no trees; shelter was available in the form of four 10-meter long tarps running along the length of the range at 10-meter intervals. Feed and water were provided ad-lib indoor and maize silage and/or carrots was provided as roughage under the first shelter of the outdoor range three times a week. Live observations of range use were carried out weekly, recording the number of hens outdoors and their distance from the pophole. Furthermore, assessment of plumage condition, as part of a welfare assessment protocol, was performed by four observers on all hens at 17 and 38 weeks of age. Preliminary statistical analysis were carried out in the software SAS using mixed models. The models included the fixed factors hybrid and age and the random factors pen and observer. Tukey test was used for post hoc testing. The range use in week 38 showed that while the total number of hens observed outside did not vary with hybrid, DW used shelters more than BB (mean ± SD: 15.1 ± 12.1 hens vs. 10.8 ± 7.5 hens; p = 0.002). Furthermore, BB ranged further away from the house than DW (mean ± SD: 4.47 ± 5.34 BB hens observed > 60 m away from the pophole vs. 1.23 ± 2.61 DW hens observed > 60 m away from pophole; p < 0.0001). Regarding plumage condition, there was an interaction of hybrid and age: while both hybrids had lower scores, (i.e. better plumage condition) at 17 weeks compared to 38 weeks of age (p < 0.001), BB had better plumage condition than DW at each time point (p < 0.001; lsmeans plumage score ± SE: BB17 = 0.98 ± 0.29; DW17 = 1.37 ± 0.29; BB38 = 4.2 ± 0.29; DW38 = 5.8 ± 0.29). These preliminary results indicate that DW are less explorative/more fearful compared to BB and highlights the need for breed-specific management such as greater shelter provision for DW. This, combined with the better plumage condition of BB, suggests that BB is a breed more robust to the environment of organic production compared to DW hens.